[web] render thread avatars in the community drawer

Summary:
render thread avatars in the community drawer

This diff won't be landed until avatars is given the green light to be released

Depends on D7208

Test Plan:
Please view the screenshots to see the changes I made:

Before:

After:

Reviewers: atul, ashoat

Reviewed By: atul

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D7209